Injection molding of parts, e.g., produced from plastic, involves the use of a press and a mold. In accordance with the present invention, the mold is a block having mated top and bottom sections referred to as a mold base. The mold base is provided with a pocket, part of which is in each of the top and bottom sections for receiving mold inserts, also in two-part top and bottom sections, in which a cavity is cooperatively formed to define a part to be molded. The mold base also includes a sprue that receives molten plastic and conveys the molten plastic to an inter-connected passage in the mold insert that leads to the cavity. Other ports or openings in the base provide access for connection of cooling water fittings secured to passages in the insert to cool the molten plastic in the cavity. Following the cooling and thus the setting of the plastic, the two sections of the mold base are separated (the plastic part residing in the bottom section of the mold insert which resides in the bottom section of the mold base). Ejector pins are extended from the mold base and through the mold insert to engage and unseat the plastic part. The plastic part having been removed from the cavity, the ejector pins are then reseated with the reseating of the two sections of the mold base. The cycle is then repeated.
The locations of the ports (for connection to the molten plastic and water) and the ejector pins are optimally located for the particular part being molded. As will be appreciated, such ports and ejector pin locations require cooperative design as between the mold base and mold insert. Thus, it has been customary that for every part that is to be produced, a mold base and mold insert therefore is custom designed and that mold base and mold insert is dedicated to the production of that part only.